The Privet's Leaves Are Yellow

Privets have fragrant white blososms in spring.

If you have a single privet shrub (Ligustrum spp.) or a hedge made up of these evergreen shrubs, seeing leaves start to turn yellow can be troubling and may be a warning sign of a problem that needs attention. The first step is to identify the cause of the leaf discoloration, which can stem from a disease, a cultural problem or infestation by a pest that damages foliage. In many cases, simply adjusting how you take care of your privet can solve the problem.

Fungal Disorders

Privets are susceptible to several fungal disorders, such as leaf spot and root rot, that can cause leaves to turn yellow. When the problem is severe, leaves may blacken and die. Proper spacing of plants helps ensure good air circulation, so that foliage dries quickly after rain and fungus doesn't grow. The Japanese privet (Ligustrum japonicum) becomes about 8 feet wide, while the California privet (Ligustrum ovalifolium) can be up to 15 feet wide, so if you're growing either type as a hedge, space plants at least 8 and 15 feet apart, respectively. If your privets are already planted too closely, remove every other plant from a hedge to improve air circulation. You can also discourage fungal growth by watering with a soaker hose or drip irrigation, to keep foliage dry, and by clearing plant debris from under plants regularly.

Pest Problems

Privets are susceptible to several pests that may cause yellowing of leaves. For example, microscopic spider mites weave visible webs on leaves, causing them to yellow and die back if not controlled. Other pests such as thrips and whiteflies can also infest privets. If you examine the plant, you might see these tiny insects hopping and flying between leaves. They suck plant juices, damaging foliage and causing leaves to yellow and eventually drop. These soft-bodied pests can be controlled by spraying the privet with insecticidal soap, diluted at a rate of 6 tablespoons per gallon of water. Wet all plant parts until they're dripping, ensuring you cover both surfaces of all leaves, and repeat the application every 2 weeks as needed.

Nutrient Deficiencies

If you see yellowing of leaves on a privet that's accompanied by spindly, poor new growth, but no other signs of disease or pests, the likely cause is poor soil nutrients. A deficiency in any of several minerals can cause yellow leaves; these include nitrogen, potassium and phosphorus, as well as some of the trace minerals, such as magnesium and manganese. Keeping plants well mulched with an organic material such as compost or composted manure can help correct these problems, but this can take several seasons. Privets don't usually need regular fertilization, but if you see signs of nutrient deficiency, fertilize the plants in early spring with a granular 10-10-10 formula that also contains trace minerals and is labeled appropriate for broadleaf shrubs. Apply at a rate of 2 to 4 pounds per 100 square feet of area under the plant's canopy, but check your label for additional directions.

Other Issues

The California privet and Japanese privet are deciduous shrubs that are usually tough and hardy. They grow in U.S. Department of Agriculture plant hardiness zones 5 through 8 and 8 through 10, respectively. Both are versatile garden plants that thrive in sun or shade and attract butterflies during the growing season. But both plants are potentially invasive in some parts of the U.S. and may spread by self-seeding. Japanese privets can also spread and become large thickets that can invade naturalized areas; for this reason, they aren't good choices to plant near the edge of a forested area.

About the Author

Joanne Marie began writing professionally in 1981. Her work has appeared in health, medical and scientific publications such as Endocrinology and Journal of Cell Biology. She has also published in hobbyist offerings such as The Hobstarand The Bagpiper. Marie is a certified master gardener and has a Ph.D. in anatomy from Temple University School of Medicine.